Top 65 Apache Kafka Interview Questions And Answers

Apache Kafka has become a popular choice among working professionals looking for job opportunities in the data processing.

This article has assembled the most famous Apache Kafka interview questions and answers for both freshers and experienced to help you ace the Apache Kafka interview questions.

Table of Contents

Q.1 What is Apache Kafka?

Kafka is an open-source message broker application developed by Apache software. It is written in Scala and is a distributed publish-subscribe messaging system. Kafka communicates between client and server using a high-performance, simple, language-agnostic TCP protocol.

Q. 2 Enlist the several components in Kafka.

Kafka has four major components:

1. Topic – same type message stream or collection

2. Producer – who publish messages

3. Brokers – the Kafka server where the published messages are stored

4. Consumers – who subscribe to topics and pull data from brokers.

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Q. 3 What is an Offset?

An uncomplicated integer number assigned to preserve the current consumer position is an Offset. The latest record sent to a consumer by Kafka in the most recent poll is the current offset.

Q. 4 In which language the Kafka Apache software is written?

Kafka is written in two programming languages – Scala and Java.

Q. 5 Explain the role of the offset.

Offset is defined as the sequential ID number given to the messages that help their unique identification within the partition.

Q. 6 What is a Consumer Group?

A Kafka consumer group is a specific consumer group of Kafka consumers that have subscribed to the same topics. This concept is exclusive to Apache Kafka.

Q. 7 Is it possible to use Kafka without Zookeeper?

No. We cannot bypass Zookeeper to connect to Apache Kafka directly.

Q. 8 What does the Zookeeper server do in Kafka?

The zookeeper server is responsible for building coordination between multiple nodes inside a cluster and recovering previously committed offset when any node fails.

Q. 9 What do you know about Partition in Kafka?

Kafka broker has a few partitions, each of which can be either a replica or leader of a topic.

Q. 10 What is the difference between partition and replica of a topic in Kafka cluster?

A partition is a single piece of Kafka’s topic that helps in parallelism when we read from issues. They determine the number of consumers that the Kafka consumer group consists of, data production, and consumption rate.

A replica is a copy of the partition that cannot be written to or read. They create data redundancy which means that, for n replicas of a topic, n-1 brokers can fail before any data loss.

Top Apache Kafka Interview Questions And Answers

Q. 11 Why is Kafka technology significant to use?

Advantages of Kafka are:

  • High Throughput so that there is no requirement for large hardware,
  • Scalability that reduced downtime by allowing on the fly addition of nodes,
  • Durability by supporting message replication,
  • Fault-tolerance as Kafka nodes are resistant to failure inside a cluster, and
  • Low Latency to handle messages with milliseconds of Latency.

Q. 12 What is a partition of a topic in Kafka Cluster?

A single piece of Kafka topic is a partition, and the number of partitions is configured based on per topic.

Q. 13 What is a topic in Kafka?

A feed name or category to publish records is called a topic, and each topic is maintained in partitioned logs of Kafka. Topics can have zero, one, or many subscribers based on consumers.

Q. 14 What are the main APIs of Kafka?

Kafka has four core API: Kafka Producer API, Connector API, Streams API, and Consumer API.

Q. 15 What are consumers or users?

Any subscriber of a Kafka topic is a consumer that can read and process messages. A record will be published and delivered to the specific consumer group subscribing to it for all consumer instances.

Q. 16 Explain the concept of Leader and Follower.

The concept of leader and follower are pretty simple. The central Kafka server acts as a leader, and other servers are the followers.

Q. 17 What ensures load balancing of the server in Kafka?

In case of a leader failing to perform read and write data requests, then one of the followers takes over and performs load balancing of the servers.

Q. 18 List some use cases of Apache Kafka?

Apache Kafka has the following use cases:

  • Tracking and logging
  • Event streams
  • Message queue

Q.19 What roles do Replicas and the ISR play?

Replicas are a list of nodes that replicate the log for a particular partition irrespective of whether they are a leader or not. At the same time, ISR or In-Sync replicas is a set of message replicas synced to the leaders.

Q. 20 Why are Replications critical in Kafka?

Replication ensures that the published messages are not lost and can be utilized in case of any fault, frequent software upgrades, program error, or machine error.

Top Apache Kafka Interview Questions And Answers

Q. 21 If a Replica stays out of the ISR for a long time, what does it signify?

It means that the leader has data accumulated faster than the fetch data rate of the follower.

Q. 22 What is the process for starting a Kafka server?

We first need to start Zookeeper from bin/zookeeper-server-start.sh config/zookeeper.properties.

Now starting Kafka server from bin/Kafka-server-start.sh config/server.properties.

Q. 23 Explain what a partitioning key is?

The partitioning key is used to validate the message partition and direct it to the destination by accessing the partition Id using a hashing-based partitioner.

Q. 24 In the Producer API, when does QueueFullException occur?

When the message brokers cannot handle the overflow of messages from the producer, then QueFullException occurs. To ensure the exception doesn’t happen, one must use multiple brokers as the producers don’t have any limitations.

Q. 25 Explain the role of the Kafka Producer API.

It is used to perform the producer functionality using one API call to the client request by combining the efforts of Kafka.producer.async.Async Producer and Kafka.producer.SyncProducer.

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Q. 26 What is the main difference between Kafka and Flume?

Even though both are real-time processing software, the main difference between Kafka and Flume is that Kafka is more scalable and durable when it comes to messaging.

Q. 27 Is Apache Kafka a distributed streaming platform? If yes, what can you do with it?

Kafka is a distributed streaming platform that allows us to store lots of records with no storage issues, push records quickly, and process records in real-time.

Q. 28 What can you do with Kafka?

Using Kafka, we can perform data transmission between two systems using a real-time stream of data pipelines and build a real-time streaming platform.

Q. 29 Explain the Kafka architecture?

Kafka is a distributed system holding multiple brokers and topics, each of which contains multiple partitions. Using this, producers and consumers can exchange messages at the same time and allow seamless execution.

Q. 30 What is the purpose of the retention period in the Kafka cluster?

Kafka clusters retail all published records irrespective of whether they have been consumed or not. The retention period in the configuration management setting is used to discard these messages to create free space in the cluster.

Top Apache Kafka Interview Questions And Answers

Q. 31 What are the main components where the data is processed seamlessly in Kafka?

Kafka data is processed seamlessly in Producers and Consumers.

Q. 32 Explain how you can get exactly-once messaging from Kafka during data production?

By avoiding duplicates during data consumption and production, you can get exactly-once messaging from Kafka. In data production, if you avail a single writer per partition and include a primary key in the message, you can ensure precisely one semantics.

Q. 33 What is a Kafka message?

Byte arrays used by developers to store objects in Avro, String, or JSON formats are called Kafka messages.

Q.34 Explain the maximum size of a message that Kafka can receive?

Kafka can receive a maximum size of 1,000,000 bytes of messages.

Q. 35 What are the types of the traditional method of message transfer?

The traditional messaging technique is of two types:

Queuing: In this method, a pool of one or more consumers read a message from the server, each of which is sent to one of them.

Publish-subscribe: Messages are broadcasted to all consumers.

Q. 36 What does ISR stand for in Kafka’s environment?

In Sync replicas or ISR are a set of message replicas that are synced to become leaders.

Q. 37 Is Apache Kafka an open-source stream processing platform.

Yes, Kafka by Apache is an open-source stream processing platform.

Q. 38 What is Geo-Replication in Kafka?

Kafka uses MirrorMaker to create message replicas across multiple data centers and cloud regions to use as active/passive backups, support data locality requirements, and place data closer to users.

Q. 39 What is the message broker?

It is a server that stores publisher messages.

Q. 40 Highlights of Kafka system?

Kafka provides:

  • High performance
  • Low Latency
  • Scalable storage

Top Apache Kafka Interview Questions And Answers

Q. 41 Explain Multi-tenancy?

Multi-tenancy is a Kafka solution that can configure topics for producing and consuming data and providing quota support.

Q. 42 What is the role of Consumer API?

Consumer APIs permit applications to subscribe to one or more topics and process the stream of records produced.

Q. 43 What does serDes mean in Apache kafka?

SerDes or serializer deserializer is provided for records for every Kafka stream and materializes the data for recorded values whenever necessary.

Q. 44 Explain the role of Streams API?

Streams API permits applications to act as a stream processor and consume input streams from one or more topics to produce an output stream.

Q. 45 What is the role of Connector API?

Connector API helps build reusable producers and consumers and runs them to connect with Kafka topics with existing data systems or applications.

Q. 46 Explain Producer?

Producers publish data to their chosen topics and select the records in topics to assign to partitions.

Q. 47 How can you send large messages with Kafka (over 15 MB)?

To send large messages, i.e., over 15 MB, three or four properties need to adjust:

  • Broker side – message.max.bytes and replica.fetch.max.bytes
  • Broker side per topic – max.message.bytes.
  • Consumer side – fetch.message.max.bytes

Q. 48 Compare: RabbitMQ vs Apache Kafka

RabbitMQ is Kafka’s alternative software that offers a performance rate of 20,000 messages/second. However, unlike RabbitMQ, Kafka is more durable, highly available, and distributed, allowing data sharing and replication. Also, Kafka has a performance rate of 100,000 messages/second.

Q. 49 Compare: Traditional queuing systems vs. Apache Kafka

Traditional queuing systems delete messages from the end of the queue once the processing completes. They don’t permit logic processing based on similar messages or events.

On the other hand, Apache Kafka doesn’t remove messages once the consumer receives them and allows messages to persist. It permits logic to be processed based on similar events or messages.

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Q. 50 Why Should we use Apache Kafka Cluster?

Apache Kafka has the following benefits:

  • It can overcome the challenges of collecting and analyzing large volumes of data.
  • It can generate alerts and report operational metrics.
  • It allows continuous processing of streaming data for topics.
  • It can convert data into the standard format.
  • It tracks web activities by storing or sending events for real-time processes.

Top Apache Kafka Interview Questions And Answers

Q. 51 What is the Kafka cluster?

All the published records, irrespective of whether they are consumed or not, are helpful in a cluster using a configurable retention period.

Q. 52 Explain the term “Log Anatomy.”

Apache Kafka interview questions

Logs are partitions in which the data source writes messages. At any time, one or more consumers can read from the logs.

The above diagram shows that a log is written by a data source and is read by consumers at various offsets.

Q. 53 What are some alternatives to Apache Kafka?

Kafka is the best and widely used of all its alternatives such as RabbitMQ, Active MQ, ZeroMQ, etc.

Q. 54 Explain how to Tune Kafka for Optimal Performance.

Kafka can be tuned by tuning its various components such as:

  • Tuning Kafka consumers
  • Kafka brokers tuning
  • Tuning Kafka producers

Q. 55 State Disadvantages of Apache Kafka.

Some of the disadvantages of Apache Kafka are:

  • Issues with message tweaking
  • Lack of pace
  • No complete set of monitoring tools
  • No support for wildcard topic selection

Q. 56 What are the advantages of Kafka technology?

Some of the advantages of Kafka are:

  • Kafka is fast and comprises brokers, each of which can handle megabytes of data.
  • It is robust
  • It has a distributed design
  • It is scalable and durable
  • Having a large dataset can help with better analyzing.

Q. 57 Enlist all Apache Kafka Operations.

Apache Kafka performs the following operations:

  • Distinguished turnoff
  • Retiring servers and data centers
  • Mirroring data between clusters
  • Addition and deletion of Kafka topics
  • Finding consumer position
  • Automatic data migration

Q. 58 Explain Apache Kafka Use Cases?

Apache Kafka interview questions

From the above use case, we can see that Kafka mainly has three use cases:

Kafka Metrics: It allows Kafka’s use for operational data monitoring and to produce centralized feeds using the operational data.

Kafka Log Aggregation: It gathers logs from multiple systems and services across an organization.

Stream Processing: Kafka is durable and hence is helpful in stream processing.

Q. 59 Some of the most notable applications of Kafka.

Netflix, Oracle, and Mozilla are some of the most notable applications of Kafka.

Top Apache Kafka Interview Questions And Answers

Q. 60 Features of Kafka Stream.

Kafka has the following features:

  • The streams are fault-tolerant and highly scalable and are equally viable for small, medium, and large use cases.
  • You can write standard Java applications.
  • Kafka can be deployed to the cloud, VMs, containers, and bare metal.
  • It has only a single processing semantics.
  • It is fully integrated with Kafka security.

Q. 61 What is the Importance of Java in Apache Kafka?

Java language is used in Kafka to provide high processing rates and good community support.

Q. 62 State one best feature of Kafka.

Having a “Variety of use cases” is the best feature of Kafka. Kafka manages a variety of use cases that are common for a data lake.

Q. 63 Explain the term “Topic Replication Factor.”

Topic replications are an essential aspect that should be considered while designing a Kafka system. Thus, if for some reason a broker goes down, other replicas can substitute for it.

Q. 64 Explain some Kafka Streams real-time Use Cases.

Some of the real-time use cases are:

LINE: The LINE application uses a central data hub for servicing.

The New York Times: Kafka is used to storing and distributing data in real-time.

Zolanda: It uses an Enterprise Service Bus (ESB) to maintain online fashion retailers.

Q. 65 What are Guarantees provided by Kafka?

Some of the guarantees by Kafka are:

  • The consumer can see the records in the same order as the records stored in the log.
  • Kafka can tolerate up to N-1 server failures without losing any records committed to the log.
  • The order for messages sent by a producer API will be the same for a particular topic partition.

Conclusion

We hope that our article on Apache Kafka interview questions can help you ace your Kafka interviews. 

You can also watch the Kafka tutorial to understand better the Kafka software developed by the Apache software foundation.

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